Programmable fluidic logic controlled machine tool

ABSTRACT

A program controlled automatic machine tool having three carriages respectively movable parallel to X, Y and Z axes that are perpendicular to each other. The X and Y carriages are horizontally movable along their respective axes to position a workpiece with respect to a cutting tool carried by the vertically movable Z carriage. A program on a suitable input record, such as punched paper tape, comprises a sequence of multi-digit X-position instructions and Y-position instructions as well as a Z-carriage motion instruction and suitable ancillary instructions. Each X and Y position instruction is entered into a fluid logic circuit that controls movement of the corresponding X or Y carriage. The carriages are commanded by the fluid logic circuits to move to the instructed positions. Position transducers associated with the respective X and Y carriages provide information to the fluid logic circuits as to the carriage positions. The carriage positions are compared to the position instructions and when correspondence is obtained for both X and Y carriages the Z carriage is enabled to cause a cut to be made in the workpiece. The procedure is repeated until all instructions in the sequence have been carried out.

United States Patent [1 1 Hicks et a1.

[ PROGRAMMABLE FLUIDIC LOGIC CONTROLLED MACHINE TOOL [75] Inventors: Morris lhliclrs, Brook R se TIi CTILE Veque, Cleveland, both of Ohio [731 est F5229; ti lqnsfiQ iv nln Qlsy and Ohio [22] Filed: June 23, 1970 211 Appl. No.: 49,098

52 us. Cl. 90/113 c, 91/37 [51] Int. Cl. B23c 1/00 [58] Field of Search 83/71, 399; 234/89,

[56] References Cited UNlTED STATES PATENTS 3,475,996 11/1969 Wheeler 91/37 X 3,606,817 9/1971 Langley 3,463,051 8/1969 Jones et a1. 91/37 X 3,415,163 12/1968 Seivemon Inaba et al. 91/388 X 3,174,406 311965 Hague et al 9l/37X 3,198,084 8/1965 Hague et 211...

3,583,281 6/1971 Hicks et al. 90/13 C Primary Examiner-Andrew R. Juhasz Assistant Examiner-Z. R. Bilinsky Attorney-Bosworth, Sessions, Herrstrom & Cain [451 Aug. M, 1973 1 STRACT A program controlled automatic machine tool having three carriages respectively movable parallel to X, Y and Z axes that are perpendicular to each other. The X and Y carriages are horizontally movable along their respective axes to position a workpiece with respect to a cutting tool carried by the vertically movable Z carriage. A program on a suitable input record, such as punched paper tape, comprises a sequence of multidigit X-position instructions and Y-position instructions as well as a Z-carriage motion instruction and suitable ancillary instructions. Each X and Y position instruction is entered into a fluid logic circuit that controls movement of the corresponding X or Y carriage. The carriages are commanded by the fluid logic circuits to move to the instructed positions. Position transducers associated with the respective X and Y carriages provide information to the fluid logic circuits as to the carriage positions. The carriage positions are compared to the position instructions and when correspondence is obtained for both X and Y carriages the Z carriage is enabled to cause a cut to-be made in the workpiece. The procedure is repeated until all instructions in the sequence have been carried out.

25 Claims, 37 Drawing Figures Patented Aug. 14, 1973 14 Sheets-Sheet 1 Fig. l

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14 Sheets-Sheet 14 INVENTOR-i 30 M02215 2, were BY JOSEPH c, 45 visas HWMA aX/n .qv-v-oeusrs.

PROGRAMMABLE FLUIDIC LOGIC CONTROLLED MACHINE TOOL The present invention relates in general to apparatus embodying a control system wherein information read from coded input record such as punched tape or the like is supplied to fluidic data processing circuit means that in turn controls the operations of a utilization device such as a machine tool or the like, in which a numerically defined program of successive motions to be executed along a path is represented on successive blocks of, and read from the input record into means that governs the drives for the movable elements of the machine tool.

In general, such numerical controls for machine tools embody electrical elements such as electrical switches, relays, transistorized units and the like. They are very susceptible to unstable conditions.

- For example, many, if not all of the electrical numerical control systems on the market now are susceptible to malfunctioning if there should be a substantial change in the voltage or the current that is supplied to them, originating either from the power source or from internal causes in the system. In other cases, electrical switches or relays having movable parts are susceptible to malfunction if thy are exposed to dust or other contaminants.

When it is realized that machine tools employing a numerical system usually cost many thousands of dollars and are employed in machining expensive work, the malfunctions can either damage the machine or cause the work to be wrongly machined, in either case with substantial economic losses.

SUMMARY OF THE INVENTION According to the present invention, the desired numerical control of movable parts of machine tools or the like to achieve the desired positioning and rates of movement of the parts is achieved by the use of a system in which electrical elements are largely, and if desired, completely eliminated and in which the desired positioning andmovements are achieved by use of fluid logic elements arranged in unique manners in fluid logic circuit means.

More particularly, the invention provides automatic programmable apparatus for performing cutting operations on a workpiece, comprising first and second holders, of which one of the holders is a work holder and the other is a tool holder, the first of the holders being movable relatively to the second holder, program input means for providing a positioning instruction to the first holder, means associated with the first holder for providing information as tothe actual position of the first holder, fluid logic circuit means for comparing the actual position of the first holder to the position instructions and providing fluidic signal outputs accordingly, and means responsive to such signal outputs for controlling the movement of the first holder in response to a mismatch between the actual position of the first holder and its instructed position. The apparatus may be made to carry out a sequence of operations that are programmed on the program input means.

According to another aspect, the program input means can be programmed to move the second holder to cause its tool to make a cut in the workpiece in response to correspondence between the actual position and the instructed position of the first holder and in response to motion instruction from the program input means.

According to a preferred embodiment, there are three holders or carriages, movable along different axes, two of which carriages are movable in at least two directions, cooperate to position the workpiece. The third carriage carries the cutting tool. Each of the two carriages that act to position the workpiece has its own position transducer, and the tool holding carriage is controlled from the program input means.

DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the invention will be apparent from the following description of a preferred embodiment of the invention in connection with the accompanying drawings in which:

FIG. I is a side elevation of a machine tool embodying the invention, which may be employed as a vertical spindle drilling or milling machine;

FIG. 2 is a front elevation of the machine tool to the same scale as FIG. I; I I

FIG. 3 is a partial plan from line 3-3 of FIG. 2 and to the same scale;

FIG. 4i is a detail of a view of a carriage position transducer from line 44 of FIG. 2;

FIG. 5 is an enlarged view, partially in section, along line 5-5 of FIG. 1 of a portion of horizontally movable lower carriage and a higher horizontally movable carriage slidably mounted on the lower carriage, showing the means for guiding the upper carriage and showing portions of each of the carriage position transducers;

FIG. 6 is a detail, along line 6-6 of FIG. 4i, of a portion of one of the carriage position transducers;

FIG. 7 is a fragment to an enlarged scale of a piece of control tape showing the numerical coding system used on the tape;

FIG. 8 is a fragment of another piece of control tape showing an illustrative arrangement or format used for the coding of a block of information;

FIG. 9 is a schematic block diagram illustrating the control system as applied to one of the horizontally movable carriages of the illustrated apparatus;

FIG. III is a block diagram indicating the system for reading out the block number or sequence number of the operation;

FIG. 1 I is a block diagram illustrating the control system for the vertically movable carriage that carries the tool carrying spindle and for the tape indexing mechanlsm;

FIG. 12 is a sectional elevation along line 12-12 of FIG. I3 and to an enlarged scale, of the tape reader;

FIG. I3 is a section along line 13-13 of FIG. I2; FIG. M is a detail along line I4-M of FIG. 12;

FIG. 15 is a portion of the cylindrical surface of the transducer drums indicated in FIG. 2 as A, showing a portion of the hole pattern in the drum;

FIG. I6 is a similar view of a portion of the surface of the transducer drum indicated in FIG. 2 as B, showing a portion of the hole pattern in the drum;

FIG. 17 is a view of the portion of the surface of the third drum indicated in FIG. 2 as C, showing an elongated hole pattern in the drum;

FIG. I8 is a sectional elevation to an enlarged scale of a portion of a drum and its associated drum reader, along line I8-Ifl of FIG. 4;

FIGS. IQa-Ifih illustrate the symbols used in the following fluid logic circuits;

FIG. 20 is a schematic diagram of one of the digit read and null fluid logic subcircuits used in a fluid logic circuit for controlling the position of one of the horizontally movable carriages of the illustrated apparatus;

FIG. 21 is a diagram of another digit read and null circuit used in conjunction with several of the circuits of FIG. 20 in a fluid logic circuit for controlling the position of one of the carriages;

FIG. 22 is a diagram showing a major fluid logic circuit, embodying the subcircuits of FIGS. 20 and 21, for controlling the position of one of the horizontally movable carriages;

FIG. 23 is an illustrative chart of the program steps. that might be followed when the machine is used for drilling;

FIG. 24 is an illustrative chart of the program steps that might be followed when the machine is used for milling;

FIG. 25 is a diagram illustrating the circuit for the visual read-out system shown in FIG. 10;

FIG. 26 is a schematic representation of the read-out element for giving a visual reading of a digit that is read from the tape by the circuit of FIG. 25;

FIG. 27 is a diagram of a partial circuit for controlling one of the clutches of the drive system shown in FIG.

FIG. 28 is a diagram of a partial circuit for controlling the operation of the tool spindle drive motor;

FIG. 29 is a diagram of the circuit for controlling the operation of the spindle carriage; and

FIG. 30 is a diagram of the circuit used for controlling the operation of the tape index cylinder.

GENERAL ARRANGEMENT For the purpose of illustration, the invention is disclosed hereinafter in connection with a vertical toolholding spindle type of machine tool in which the work is mounted on a generally horizontal table that is movable along two generally horizontal axes, and in which there is a rotating tool such as a drill bit or a milling cutter that is movable along a generally vertical axis if desired, into contact with the work to drill a hole or mill a surface in the work at a location or in a direction as desired. The present invention will be discussed in connection with the moving and positioning of the work and the tool relative to each other and operating both according to a prerecorded coded program.

' As shown in FIGS. 1 and 2, the illustrated apparatus comprises a machine tool M connected to a decoding device such as a tape reader R that reads prerecorded program data on an input record such as a tape I having patterns of holes that contain the program record.

The illustrated vertical spindle machine tool comprises a conventional base 10. A rotatable tool holder or spindle 12, adapted to carry a tool such as a drill bit T shown in full lines, or a milling cutter T which may be a side mill cutter shown in broken lines, is mounted on a carriage 13 that is vertically movable on the base by means to be described. A work holder 14 taking the form of a work table to which the work W may be clamped by suitable conventional means, is horizontally movable, by means to be described, parallel to two horizontal axes; one axis indicated as X parallel to the front face of the machine and shown by the arrows in FIG. 2; and the other axis indicated as Y" at right angles to axis X as shown by the arrows in FIG. 1. Both of these axes are at right angles to the vertical axis 2" along which the spindle I2 is moved (FIG. I).

Worktable 14 is supported from base 10 and power actuated as follows: A first carriage 15, the Y carriage, is slidably mounted on the.base I0 by conventional guide means 16 for movement in a fixed guided path parallel to the Y axis and is positively moved by a hydraulic motor MY mounted on base 10 and operatively connected to carriage 15 to move it as required when the motor is suitable actuated. A second carriage 17, the X carriage, the upper portion of which constitutes work table 14 in this embodiment, is slidably mounted on carriage 15 by conventional guide means 18 for movement parallel to the X axis in a fixed guided path on carriage 15. The second carriage is positively moved by hydraulic motor MX mounted on first carriage l5 and operatively connected to carriage 17 to move it as required when the motor is suitably actuated.

The carriage 13, the Z carriage, carrying spindle I2 is a third carriage and is slidably mounted on base 10 by conventional guide means 19 for movement in a fixed guided path along the vertical Z axis, and is positively moved by hydraulic cylinder MZ secured to base 10 and having a piston rod 21 fixed to arm 22 on carriage l3. Spindle 12 is rotated as required by electric motor 23 on carriage 13 through motor pulley 24, spindle pulley 25, and belt 26 engaging these pulleys.

The hydraulic motors MX, MY and hydraulic cylinder MZ are powered by hydraulic fluid under suitable pressure, as of from about I00 to about 500 pounds per square inch (psi) supplied from a suitable conventional source identified as 27 in various figures.

The workpiece W is moved by the work table 14 parallel to either or both the X or Y axis to one or more predetermined positions established by tape I and read by reader R, where the tool can be brought into contact with the work, and the too] if a drill can be rotated to drill one or more holes in the work at desired locations on the work, or the tool if a milling cutter can be rotated to cut the work for a desired depth and distance while the work is moved according to a program on the tape. According to the present invention, the workpiece may be so moved at a variable speed.

The means utilized in the illustrated apparatus are described below for translating the data on the tape into signals that control the motors MX and MY, cylinder MZ and motor 23 to accomplish this in the illustrated apparatus.

DRIVE MEANS AND POSITION TRANSDUCER FOR A CARRIAGE FIGS. 4-6 illustrate the means shown for driving, from motor MX, the carriage 17 parallel to the X axis on carriage l5, and for driving a series of rotatable carriage position transducer drums A, B and C used in comparing the position of carriage 17 with the data on the tape I.

Motor MX, a reversible hydraulic motor of conven tional type, is mounted on carriage I5, and is adapted to rotate a screw member 28, having a helical thread 29 that is rotatably mounted by bearings 31 on carriage l5. Carriage 17 has secured to it a nut member 32 that engages the thread 29 so that rotation of screw member 28 in either direction will cause carriage 17 to move in its guided path on carriage 15 parallel to the X axis, in a direction depending on the direction of rotation of member 28. Carriage 15 also carries a fluid-actuated brake 33 comprising a braking member 34 adapted to contact member 28 and to be actuated by fluidactuated piston 35', under normal circumstances there is no force applied to the piston to produce braking action.

The free end of shaft 36 of motor MX has flat surfaces 37 to permit engagement and turning of the shaft by a removable crank or wrench.

Carriage 15 also carries a carriage position transducer 38 that compares the position of the carriage 17 along the X axis with signals from the tape I giving information as to the desired position of carriage 17. Transducer 38 is actuatable by screw member 28. It comprises a bracket 39 fixed to carriage 15, which bracket rotatably supports a first shaft 41 coaxial with member 28 and adapted to be coupled to and disconnected from member 28 by a conventional fluid actu-- ated clutch 42. The uncoupled end of shaft 41 has flat surfaces 43 to permit engagement and rotation of the shaft by a disconnectible crank or wrench.

Shaft 41 is adapted to be braked and halted as required by a brake 44 comprising a braking member 45 adapted to engage the shaft and be actuated by a fluid actuated piston 46.

A gear 47 fixed to shaft 41 drives a pinion 48 rigidly mounted on a second parallel shaft 49 journaled in bracket 39. An openended cylindrical transducer drum A is mounted on a projecting end of shaft 49 to rotate with it. Shaft 49 also rigidly carries a worm 51 that engages a worm wheel 52 mounted on a cross shaft 53 journaled in bracket 39 (FIGS. 5 and 6). Shaft 53 also rigidly carries a worm 54 that drives another worm wheel 55 on a shaft 56 parallel to shafts 41 and 49 and journaled in bracket 39 (FIG. 6). Shaft 56 rigidly carries a second cylindrical open-ended transducer drum B. Shaft 56 also carries a pinion 57 that drives a gear 58 mounted on a shaft 59 that carries a third cylindrical open-ended transducer drum C.

It is apparent that rotation of screw member 28 by motor MX orby wrench or crank power applied to shaft 36 will cause carriage 17- to move parallel to the X axis on carriage l5, and will also cause rotation at different rates of the three drurns A, B, and C. In the illustrative example provided by this disclosure, the threads on the screw member 28 and the gearing driv-' ing the drums are such that one inch of travel of carriage 17 on carriage 15 results in revolutions of drum A, in one-tenth of a revolution of'drurn B, and in one-thirtieth of a revolution of drum C.

An identical arrangement is employed to move carriage from motor MY on the frame 1 in a fixed path parallel to the Y axis. A transducer 38 is associated with carriage 15 to compare its position on base 10 along the Y axis with signals from the tape I giving information as to the desired position of carriage 15; this transducer is identical with that described as associated with carriage 17, and its illustrated parts have reference riety of input records, such as tapes or cards, containing prerecorded program information that can be utilized in the illustrated apparatus and system. The illustrative tape is a known one-inch wide eight-track tape, formed of a strip of paper or other sheet material, that is widely used in the numerical control of machine tools and for other purposes, and is coded in a coding identi fied as Electronics Industries Association (EIA) coding. FIG. 7 shows a piece of such tape. The tape has a continuous line of perforated holes 611 that allow it to be driven by the sprocket of a tape drive system; it also discloses the EIA arrangement of holes 61 used for coding digits 0 through 9 and the signs plus and minus and end of block." The first four channels are assigned numerical values of I, 2, 4 and 8, and the digits 1 through 9 are made up of combinations of one or more of these numbers in a conventional Binary Coded Decimal or BCD code. Each of the numerical values making up the BCD digits will be referred to as a value. In the EIA system, the coding pattern for digits 1 9 may include holes in other channels in addition to those shown in the first four channels for parity checking purposes; however, in the interests of simplification they are not shown since they are not used in the illustrated apparatus. As indicated, certain holes in channels 5 to 8 inclusive are also used to designate plus, minus, and end of block symbols. Blocks of information controlling machine functions to be performed or functions to be indicated are coded and arranged in a predetermined pattern and recorded by punching suitable holes in the tape.

FIG. 8 shows a segment of tape illustrating the position of holes on the tape used in an illustrative block of information showing the format of the information arrangement used with the disclosed apparatus and control system. The program of instructions to the present apparatus consists of a sequential series of blocks like that shown in FIG. 8. Each block consists of 24 rows of information.

The machine carriage position control system is predicated on the use of two five-digit numbers which may be designated as X-N N N N N and Y- N,,N N N N, coded in rows 1-5 and 1111-14, respectively, of the tape. The numbers designate a position to be assumed by carriage 17 along the X axis and by carriage 15 along the Y axis, respectively. The five-digit numbers inrows 1-5 and 1141-14 will be referred to below as the X-word and the Y-word, respectively, or as the X instruction and Y instruction. The carriages may move in either a plus or a minus direction where plus is arbitrarily established as one direction of movecharacters identical to those of corresponding parts of TAPE AND TAPE READER The punched tape I (FIGS. 1, 7) is illustrative of a vament and minus is the other direction of movement.

Rows 6, 7, 5, 9, 15, 16, 17, 15, 19, 211, 23 each control two choices. The first choice is coded as plus the other choice is coded as minus Thus, the holes in row 6 of the block may be coded to designate the plus or minus direction of movement to be used for carriage 17 parallel to the X axis, and row 15 may be coded with holes indicating either the plus or minus direction of movement of carriage 15 parallel to the Y axis, and so on for all the other two-choice rows mentioned above.

Rows 21 and 22 in each block are used for coding digits N and N, of a two digit number representing the block number or sequence number of the operation to be performed; for convenience in programming, each block of information is assigned with a sequence numher representing that block of information; the information in these rows may be used to provide a visual readout of the sequence of numbers as described later.

Row 23 is coded to command the spindle 2 to rotate or be stopped during the time the machine is under the influence of that particular blocl of information. Row 20 is coded to command the vertically movable spindle carriage 13 to start a cycle of powered movement in a downward direction.

Row 24 is coded to signify to the tape reader that a block of coded information is in position in the reader and may now be read.

Row 7 designates the rate of travel, either rapid or slow, for carriage 17 that moves parallel to the X-axis. Row 16 does likewise for carriage 15 that moves parallel to the Y axis. Rows 8 and 9 are coded to provide desired action of brake 33 to prevent movement of the carriage l7; row 8 provides for braking of the carriage all the time a block of information is in effect; row 9 provides for braking action after the carriage 17 has moved to a position of correspondence between the commanded and the actual position. Rows 17 and 18 are likewise coded to provide desired braking action of carriage 15 by control of its brake 33.

After both carriages l5 and 17 reach a null condition between commanded and actual positions, information coded in row 19 determines whether the tape is immediately indexed to the next block of information. If tape index does not occur at this time, then the action is initiated by a machine movement or the action is manual.

In the illustratively coded segment of tape of FIG. 8, the X command position for carriage 17, rows 1-5, is 19.765, direction and rate of travel (rows 6 and 7) are plus" and rapid" and the brake operation, coded in rows 8 and 9, is "off" and off." The Y command position for carriage 15, rows 10 thru 14 is 07.32. Direction and rate of travel (rows 15 and 16) are minus and rapid;" and brake operation coded in rows 17 and 18, is off" and off." Row 19 commands the tape to index to the next block upon reaching an X and Y null. Rowt20 tells the Z slide not to move down upon reaching an X and Y null." Rows 21 and 22 show the sequence number to be 25. During the influence of this block of tape, row 23 indicates'the spindle is not to run.

SCHEMATIC REPRESENTATION OF CONTROL SYSTEM FIG. 9 illustrates in a block diagram the system for powering th movement of, and controlling the positioning of each of the horizontally movable carriages l5 and 17 of the illustrated apparatus from the information on the tape I. This system embodies the elements that operate from rows 1, 2, 3, 4, 5, 6, 7, 8, 9 of a block of the tape to control carriage 17. An identical system utilizes information on rows 10, 11, l2, l3, l4, l5, l6, l7 and 18 on the block of the tape to control carriage 15.

FIG. 10 illustrates in a block diagram the system that is controlled by rows 21 and 22 of the block of the tape illustrated in FIG. 8 to provide a visual indication of the block sequence number of the operation.

FIG. 11 illustrates in a block diagram the system controlled by row 19 of the tape for indexing the tape, and the system controlled by row 20 of the tape to control powered movement of the spindle carriage 13.

Referring to FIG. 9 as applicable to carriage 17, low pressure fluidic signals from coded information on the appropriate rows 1-9 of the tape I pass through a tape reader R and then to digit read and null circuits (DRN) 62 to be described later. Information passes from the reader R and the DRN circuits to a logic circuit 63 that governs operation of the controls 64 for the fluid power motor MX that drives the screw member 28 described above that positions machine carriage 17. Information from the carriage position transducer 38 also is fed into the circuits 62 as described later.

According to FIG. 10, the low pressure fluidic signals from coded information of rows 21 and 22 of the tape I passes through the reader R and thence to a decoder circuit 65 that translates the tape signals to numeric signals that are transmitted to a readout driver circuit 66 and thence to the readout unit 67.

According to FIG. 11, the low pressure fludic signals from coded information in line 20 of the tape pass through reader R, connected to a fluid logic circuit 68 that governs operations of controls 69 for cylinder MZ that moves carriage 13 along the Z axis. Information as to the status of carriage 13 passes back to the logic circuit 68. As indicated in FIG. 11, manual controls 70 are also provided to operate through the logic circuit 69 to control movement of the carriage 13.

FIG. 11 also illustrates that low pressure fluidic signals from coded information in line 19 of the-tape pass through reader R which is connected to a fluid logic circuit 71 that governs operation of controls 72 in cylinder 82 that actuates the tape indexing mechanism, information that the tape is fully indexed passes back to the logic circuit. Manual controls may also be used to initiate tape index.

Circuits for implementing the instructions in the remaining rows of the tape are more conveniently disclosed in line diagrams below.

In the illustrated embodiment, the fluidic signals preferably are pneumatic signals, such as air signals, at suitable low pressures, as between about one-half to about 5 pounds per square inch, and preferably between about one and about two pounds per square inch TAPE READER The illustrated tape reader R (FIGS. 1, l2, l3, 14) comprises a stationary body 73 in which is joumaled transversely shaft 74 that rigidly carries a gear 75. A sprocket 76, having peripheral radially extending equally spaced pins 77 adapted to engage driving holes 61 in the tape, is connected to shaft 74 through a conventional overrunning clutch 78 that engages and drives the sprocket from the shaft only when the shaft is rotated in one direction and disengages the sprocket when the shaft turns in the opposite direction. Springforced detents 79 in body 73 engaging radially and angularly spaced depressions 80 in the sprocket, are so arranged that they hold the sprocket against rotation when it is disengaged from the clutch.

A rack 81, slidably mounted on body 73' of the tape reader R, has teeth engaging those of gear 75. The rack is moved as required to turn gear 75 and shaft 74 in either direction by a double-acting fluid operated cylinder 82, the piston rod 83 of which is connected to the rack. A limit valve 84 is contacted by rack 81 at the end of its outward movement.

The tape I passes between reader body 73 and a cover 85 hinged on the body so the cover can be lifted to permit ready threading of the tape through the reader. The tape is moved through the reader by engagement of sprocket pins 77 in holes 61 of the tape when the sprocket is periodically turned in one direction. Body 73 has a chamber 86 supplied by air at a controlled pressure from a suitable source that includes conduit 87. From this chamber passages 88 extend upwardly to the surface of the body over which the tape passes, the holes being arranged in a number of rows extending transversely and at right angles to the path of travel of the tape; and equal to the number of rows in a block of information on the tape, the passages in each row being equal in number and spaced to align with any holes in the eight channels of the tape.

The hinged cover 85 has corresponding passages 89 communicating with the surface over which the tape passes and also communicating with separate air conduits 90.

The parts are so arranged that the reciprocating motion of rack 81 will cause the tape to be moved forward in the direction indicated by the arrow in FIG. I2 by predetermined incremental steps, in which at the end of each step the holes in the rows of a block of tape are aligned with coresponding rows of holes in the tape reader, so that those holes in the tape that provide signals will permit air to pass through the tape reader and out through the corresponding conduits 90.

CARRIAGE POSITION TRANSDUCER READING MEANS FIGS. 15, 16 and 17 respectively show developed partial views of the cylindrical surfaces of drums A, B and C of the carriage l5 and 17. In each surface of each drum there are openings arranged in a predetermine pattern and extending through the cylindrical drum flange to its outer cylinder surface.

Thus, in each of drums A and B (FIGS. 15, I6) there are 100 axially extending rows of generally circular holes 91 equally spaced circumferentially around the drum and there are eight circumferential tracks or channels for the holes in each row. Drum C (FIG. 17) has elongated slots 92 arranged circumferentially in three tracks corresponding to three of the first four tracks, counting from the right, of the drums A and B (FIGS. l5, 16). In the drums A, B and C for carriage 17, sets of tracks are used for digits in the X-word; in the drums for carriage 15, sets of tracks are used for digits in the Y-word.

The EIA coding system mentioned above uses a significant pattern of hole arrangements in four of the available eight tracks to codify the values 0 through 9. Each of the drums A and B, however, with two sets of four tracks for each axial row of holes, has capability of coding two digits. Drum C has a capability of coding one digit. The value 0 is coded as a hole in each of the ,second and fourth tracks. Therefore, one variation of the EIA coding system is here employed.

FIG. illustrates the hole pattern in a segment of drum A. From top to bottom of the figure, the digits represented by the hole pattern are 95, 96, 97, 98, 99, 00, Ol, 02, 03, 04, 05; therefore, with 100 rows in one revolution of the drum, all numbers from 00 through 99 can be represented. The same applies to drum lB, FIG. 16. In drum C. FIG. 17, the digits 0, l, 2, 3 are represented by coded elongated holes or slots 92.

In the illustrated embodiment, taking into account that 1 inch of travel of carriage 17 results in 10 revolutions of drum A, one-tenth revolution of drum B, and

one-thirtieth revolution of drum C, drums A, B and C for each arriage 15 or I7 can represent values from 00.000 to 39.999 inches to indicate the carriage position with respect to an imaginary reference line.

The previously indicated X-word and Y-word are five-digit numbers expressing the desired positions of carriage I7 (the X carriage) and carriage IS (the Y carriage) as recorded within a block of information on the tape. The five digit number represented by a single row of holes from the drums A, B and C of the trans ducer for one of these carriages represents the actual position of the carriage with reference to the imaginary reference line.

Drums A, B and C respectively have. associated reader members 93, 9d and 95.

FIG. I8 shows in cross section the cylindrical flange of drum A and its relation to its reader member 93 and one axially extending row of holes 91 in the drum flange.

Reader member 93 is a U-shaped member having a portion 93a extending outside the drum flange and a portion extending inside the drum flange, these portions being sufficiently close to the drum flange to prevent substantial leakage or short circuiting of air, although it is not necessary to have air-tight seals at these locations since all that is required as outputs from the reader are air signals.

Portion 93b has a chamber 96 to which air is supplied from a source including conduit 97 at a pressure preferably corresponding to that of the air supplied to the tape reader. Portion 93b has a single transverse row of holes 98 communicating with chamber 96; these holes are equal in number to the number of tracks, eight in this case, on the drum, and are aligned with an axial row of holes on the drum. A single row of holes 99 extend through the other portion 93a in alignment with holes 98, and these holes communicate with conduits As the drum rotates, it brings the holes in a row in the drum flange into alignment with the holes in the reader portion of the drum, and pneumatic signals are sent out through conduits llllllllt'in accordance with holes in the drum designating digits.

The readers for drums A and B are identical.

The same general arrangement of reader member and drum flange applies to drum C, reader member differing only in the number of holes to correspond to the number and locations of the slots 92 of the drum C.

FLUID LOGIC SYMBOLOGY For clarity, the symbols for fluid-actuated fluid logic elements used in the below described fluid logic circuits are set forth in FIGS. I9a-I9h inclusive. Symbols I90, 19b, 19c, and 19d, respectively show fluid logic el ements each being connected to a conduit providing an input power stream and indicated by a line I011 with an arrow pointing toward the element, a single output signal conduit and, opposite this conduit, one or more input signal conduits. The power stream conduits are connected to a suitable source of clean fluid, such as air, under the pressure indicated above; the source, being conventional, is not shown. FIGS. ll9a, 19b, 19c, 19d respectively show one, two, three and four input signal conduits. Each of these elements sometimes called a fluid amplifier, is of a known commercial type which, when the input power stream is operating, provides an output signal only when there is no input sig- 

1. In machine tool apparatus, a tOol holder, a work holder, said holders being relatively movable to permit a tool in the tool holder to perform a work operation on a workpiece in the work holder, program input means for providing a positioning instruction in the form of low pressure fluidic signals to at least one of said holders, said positioning instruction including a position to be assumed by said instructed holder and a direction and rate of travel to cause said instructed holder to reach the position to be assumed, a member movable in fixed relation to movement of said instructed holder for continually providing information as to the position of said instructed holder in the form of low pressure fluidic signals, means utilizing said positioning instruction signals and said position information signals for comparing said position information fluidic signals to said fluidic signals representing said position to be assumed, and means for moving the instructed holder in response to a mismatch between said position information and said position to be assumed.
 2. In machine tool apparatus, a tool holder, a work holder, said holders being relatively movable to permit a tool holder to perform a work operation on a workpiece in the work holder, program input means for providing a positioning instruction in the form of low pressure fluidic signals to at least one of said holders, said positioning instruction being provided to one of said holders to designate a position to be assumed thereby and a direction and rate of travel of said holder, a member movable in fixed relation to movement of said instructed holder for continually providing information as to the position of said instructed holder in the form of low pressure fluidic signals, means utilizing said positioning instruction signals and said position information signals for comparing said position information to said position to be assumed, means for moving the instructed holder in response to a mismatch between said position information and said position to be assumed, said program input means providing instruction to enable a work operation to be performed on said workpiece, means for causing said work operation to be performed in response to said work operation instruction and to correspondence between said position to be assumed and said position information, said work information instruction being provided to said tool holder to cause it to perform a work operation on said workpiece in response to correspondence between said position information and said position to be assumed.
 3. Apparatus as claimed in claim 2 wherein said positioning instruction is provided to said workholder to designate a position to be assumed thereby and a direction and rate of travel of said workholder, and said work operation instruction is provided to said toolholder to cause it to perform a work operation on said workpiece in response to correspondence between said position information and said position to be assumed.
 4. In machine tool apparatus, a tool holder, a work holder, said holders being relatively movable to permit a tool in the tool holder to perform a work operation on a work piece in the work holder, program input means for providing a positioning instruction in the form of low pressure fluidic signals to at least one of said holders, means associated with said instructed holder for providing information as to its position in the form of low pressure fluidic signals, said means for providing position information including a driven member that rotates in fixed relation to movement of said holder being positioned, said driven member having patterned spaced holes coded to indicate the positions of said holder being positioned, means utilizing said positioning instruction signals and said position information signals for comparing said position information to said positioning instruction, and means for moving the instructed holder in response to a mismatch between said position information and said positioning instruction.
 5. Apparatus as claimed in claim 49 wherein said position comparing means includes circuit means embodying low pressure fluidic signal responsive devices that produce a low pressure fluidic output signal condition when the signals representing said position information correspond to the signals representing said position instructions.
 6. Apparatus as claimed in claim 4 wherein said program input means provides instruction to enable a work operation to be performed on said workpiece and wherein said apparatus further comprises means for causing said work operation to be performed in response to said work operation instruction and to correspondence between said positioning instruction and said position information.
 7. Apparatus as claimed in claim 4 comprising two carriages, one movable along a first axis and the second carriage movably mounted on said first carraige for movement along an axis transverse to said first axis, said second carriage carrying said work holder, said program input means providing positioning instructions to each of said carriages, a pair of driven members rotatable in fixed relation with movement of each respective carriage for providing information as to the position of each carriage, means for comparing the position of each of said carriages to its positioning instructions, and means for moving each carriage in response to a mismatch between its position and its positioning instructions.
 8. Apparatus as claimed in claim 7 wherein said carriages are movable along mutually perpendicular axes to position said workpieve with respect to said toolholder, said program input means providing a motion instruction to said toolholder, and means for causing a work operation to be performed on said workpiece in response to said motion instruction and to corresponding between the position information and the positioning instructions of both said carriages.
 9. Apparatus as claimed in claim 4 further comprising reader means having an array of holes related to and adapted to be aligned with holes in said driven member, and means for directing low pressure fluidic flow through holes aligned in said reader means and said driven member to produce low pressure fluidic signals indicative of the position of said holder being positioned.
 10. Apparatus as claimed in claim 4 wherein said program input means includes an input record medium in the form of strand material.
 11. Apparatus as claimed in claim 11 wherein said input record medium has a series of blocks of information including said instructions recorded thereon, said information including unique identification for each block, and further comprising means for providing a visual display of said block identification.
 12. Apparatus as claimed in claim 4 wherein said program input means includes an input record medium haivng said instructions recorded thereon in the form of holes, and means for reading said holes to provide said instructions to said holders in the form of low pressure fluidic signals.
 13. The apparatus as claimed in claim 12 wherein said reading means includes an array of holes related to and adapted to be aligned with holes in said input medium such that fluidic flow is permitted through said members and said medium when the repsective holes are aligned.
 14. The apparatus as claimed in claim 12 wherein said input record medium is flexible tape having said instructions punched thereon.
 15. Apparatus as claimed in claim 12 wherein said input record medium has a series of blocks of information including said instructions recorded thereon, said information including unique identification for each block, and further comprising means for providing a visual display of said block identification.
 16. Apparatus as claimed in claim 12 further comprising drive means for moving said input record medium predetermined distance to present new instructions to said holders.
 17. Apparatus as claimed in claim 16 further comprising manually operable fluidic signal producing means for initiating operation of said drive means.
 18. In machine tool apparatus, a member movable in a path and means for producing low pressure fluidic signals indicating the position of said movable member, said signal producing means including a driven rotatable member coupled to said movable member for rotation in fixed relation to movement of said movable member, said driven member having a series of patterned spaced holes coded to represent the position of said movable member, reader means cooperating with said driven member and having patterned spaced holes related to and adapted to be aligned with holes in said driven member, and means for directing low pressure fluidic flow through aligned holes in said reader means and said driven member to produce low pressure fluidic signals indicative of the position of said movable member.
 19. Apparatus as claimed in claim 18 further comprising means for altering the position of said driven member with respect to the position of said movable member.
 20. Apparatus as claimed in claim 18 wherein said driven member comprises a cylindrical drum having a series of circumferentially spaced rows of holes, each of said rows forming a code that indicates a circumferential distance from a starting point on said drum, said drum rotating in fixed relation with movement of said movable member to indicate the position of said movable member.
 21. In machine tool apparatus, a tool holder, a work holder, said holders being relatively movable to permit a tool in the tool holder to perform a work operation on a workpiece on the workholder, program input means for providing instructions in the form of low pressure fluidic signals to at least one of said holders, said instructions including a direction and rate of travel for said instructed holder and a position to be assumed thereby and a work operation instruction, a member movable in fixed relation to movement of said instructed holder for continually providing information as to the position of said instructed holder in the form of low pressure fluidic signals, means utilizing said signals representing said position to be assumed and said position information signals for comparing said position information to said position to be assumed, means for moving said instructed holder in response to a mismatch between said position information and said position to be assumed, and means for causing said work operation to be performed in response to said work operation instruction and to correspondence between said position to be assumed and said position information.
 22. The apparatus as claimed in claim 25 further comprising means for providing a visual display of at least a portion of said instructions.
 23. In a logic element control circuit for controlling movement of movable members of a machine tool, means for providing low pressure fluidic signals representative of operation instructions for said movable members, said operation instructions including position instructions, direction of travel instructions and rate of travel instructions for a first of said movable members, fluidic circuit means repsonsive to said position instructions for causing movement of said first member toward said instructed position, means including a member movable in fixed relation to movement of said first member for continually providing low pressure fluidic signals representative of the acutal position of said first member, and fluidic circuit means for causing movement of said first member to be terminated in response to correspondence between said position instruction signals and said actual position signals.
 24. In a logic element control circuit for controlling movement of movable members of a machine tool, means for providing low pressure fluidic signals representative of pre-programmed storable operation instructions for said movable members, said operation instructions including position instructions, direction of travel instructions and rate of travel instructions for at least one of said movable members, fluidic circuit means responsive to said position instRuctions for causing movement of the instructed members toward their instructed positions, means for continually providing low pressure fluidic signals representative of the changing actual positions of said instructed members, and fluidic circuit means for causing movement of said instructed members to be terminated in response to correspondence between said position instruction signals and said actual position signals for each of said instructed members.
 25. In a logic element control circuit for controlling movement of movable members of a machine tool, means for providing low pressure fluidic signals representative of pre-programmed storable operation instructions for said movable members, said operation instructions including position instrcutions for at least one of said movable members, fluidic circuit means responsive to said position instructions for causing movement of the instructed members toward their instructed positions, means for continually providing low pressure fluidic signals representative of the changing actual positions of said instructed members, fluidic circuit means for causing movement of said instructed members to be terminated in response to the correspondence between said position instruction signals and said actual position signals for each of said instructed members, said pre-programmed storable operation instructions for said movable member including further instructions for causing movement of at least one other movable member after movement of said instructed members has been terminated in response to coincidence between said position instruction signals and said actual position signals.
 26. The circuit as claimed in claim 25 wherein said further instructed movable members include a movable member that advances the pre-programmed storable instructions. 